I just downloaded, updated and installed Magic Trackpad and Multi-Touch Trackpad Update 1.0 and BOOM...I have inertial scrolling on my Apple MacBook Pro 5,1 (late 2008)! I've been dreaming of this moment for quite a while since using my colleague's newer MacBook Pro that touted this feature. Thanks Apple for looking after the older guys with the first-gen trackpads. =)
If you have any of these models below, update away and be impressed! Supported gestures include a three-finger drag and inertial scroll for MacBook and MacBook Pro systems.

MacBook

MacBook (13-inch, Early 2009)

MacBook (13-inch, Mid 2009)

MacBook (13-inch, Late 2009)

MacBook (13-inch, Aluminum, Late 2008)

MacBook Pro

MacBook Pro (17-inch, Mid 2010)

MacBook Pro (15-inch, Mid 2010)

MacBook Pro (17-inch, Mid 2009)

MacBook Pro (15-inch, 2.53 GHz, Mid 2009)

MacBook Pro (15-inch, Mid 2009)

MacBook Pro (13-inch, Mid 2009)

MacBook Pro (17-inch, Early 2009)

MacBook Pro (17-inch, Late 2008)

In other normal tech news, just in case you haven't already heard, Apple released the "Magic Trackpad" to accompany the newer updated iMacs and Mac Pros. Paving the way for a complete mouse-less computing experience, the glass is here to stay!